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Do I dare change my tranny fluid? (Th350)

76k5blazerr

76k5blazerr

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Alright guys. My 79 blazer has a th350 and i am pretty sure that the fluid in it hasn't been changed since Jesus walked on water. Well maybe not that long, but it's obviously been awhile. The fluid smells old (but not burnt) and is not really red anymore, more of a brown. The reason I have not changed it yet is because I have heard that Tranny fluid that has not been changed after a certain amount of time will have bits of stuff in it that is the only thing keeping the clutches from slipping. The tranny drives fine, shifts good in all gears. The reason I am asking this question is I have to drive the truck 130 miles this Sunday and I really need to make it there. I want to know if I should change the fluid and filter or leave well enough alone. What would you guys do?
 
I think it is when you flush a transmission is where you'll run into issues. But I changed my 700r4 trans fluid two years ago, and my truck is running tip top with daily driving and hauled a 3700 lb trailer when I pcs'd from SoCal to eastern Washington without issue!
 
I have heard it's fine to change it, but not get a professional fluid flush. That said, my Lexus has 240 thousand miles on it without a transmission fluid change. lol.
 
I've never had one die just from dropping the pan and changing the filter and topping it back up...those 3-4 qts vs the full capacity of 10+ qts wont do much harm,its so diluted and maybe some good...I've heard all kinds of horror stories about power flushing old automatics though..
 
76k5blazerr said:
im trading it next Sunday. That's why I said it needs to make it there.
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If it was my truck, and I was planning to trade it on Sunday, and it was in good running condition, I would not be touching or modifying *anything* right beforehand. Taking even a small risk isn't worth it when it's not sticking around long enough for you to reap any benefits. And messing with the tranny may or may not turn out to be a small risk. :dunno:
 
I have my 87 K5 over 10 yrs. Never touched the tranny. Yesterday I changed the fluid and filter on my 700r4. Was pretty clean. A bit reddish brown but overall good. No shavings. Shifts sweet. I would just for piece of mind.
 
Had my turbo 350c go out after just doing a pan drop/filter change.

Aside from abuse, it had gotten antifreeze in it from a leaking rad cooler. Which I believed the clean atf washed whatever was left holding the trans together out and it calved.

But under normal circumstances I see no problem with a pan drop, id stray very far away from a flush though.
 
campfire said:
If it was my truck, and I was planning to trade it on Sunday, and it was in good running condition, I would not be touching or modifying *anything* right beforehand. Taking even a small risk isn't worth it when it's not sticking around long enough for you to reap any benefits. And messing with the tranny may or may not turn out to be a small risk. :dunno:
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Exactly. Why change something at this point? Just leave it alone imo.
 
Flushing trannys keeps tranny shops in business. All it does is suck out the old, leave the shavings and clutch material, and replace with new. Ignoring the partially clogged filter and piles of clutch material in the pan. The same goes for drain plug style changes.

Now, that MYTH has been around for years, and at one time it was truer than it is now, but these trannys and their fluid dont need that myth anymore, change it (especially since its just brown and not burnt) and forget it.
 
Ok, now I'm getting a mixed vote, I should've posted a poll. I guess what I'm asking is you guys don't see any reason that the truck wouldn't make it 130 miles on this old Tranny fluid?
 
Unless you're having some sort of trouble, and you think that changing the fluid is going to help, I don't see how this trip could benefit from changing the fluid. And there's that chance (however small) that it might mess something up, right at a pretty critical moment. Just my $0.02
 
Is this a real thing?


Also if you are trading the thing, why bother, let the next owner change it.
 
If you are driving it to sell then I would just be sure it was at the correct level and send it down the road. I don't honestly believe a trans service of any sort will kill a trans that was not already on deaths door. Its just fluid, it is a coolant, a lubricant, a friction modifier, and does have some detergent properties as well but it isn't poison
 
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